Hybrid module for watercraft

ABSTRACT

The invention relates to a hybrid module for installation between an internal combustion engine ( 6 ) and the transmission ( 4 ) of a watercraft, the flywheel being located in a conventional way in the housing of the internal combustion engine ( 6 ). It is characterized in that the hybrid module ( 7 ) is external to the housing of the internal combustion engine ( 6 ) and comprises a housing ( 8 ), a generator/motor ( 11 ) within the housing, and suitable shifting elements ( 10 ) for optionally coupling the transmission ( 4 ) with the internal combustion engine ( 6 ) and/or the generator/motor ( 11 ).

The present invention relates to a hybrid module for watercraft, which optionally permits operating the watercraft by internal combustion engine or by electric motor, or which by a compound arrangement of both engine types permits boosting or generating electricity, in particular for battery charging. The invention especially relates to an add-on module for existing internal combustion engine drive systems for watercraft to convert them to hybrid propulsion systems, or to a module which can be integrated in new propulsion systems.

In recent years there has been increased demand for emission-free propulsion systems for watercraft which are operated in ecologically sensitive areas. This trend now extends to harbour regions and protected areas and becomes increasingly relevant for commercially or privately operated watercraft, such as water taxis, supply ships or yachts.

Hybrid propulsion systems, which permit propelling a vehicle optionally either by an internal combustion engine or by an electric motor, are already state of the art. U.S. Pat. No. 5,214,358 for instance describes a generator connected to the flywheel of an internal combustion engine and provided with control circuitry for charging batteries, which in turn power a separate electric motor. This solution is not a generator/ motor for a direct electrical drive, however, but requires two separate electrical units for electrically propelling the vehicle. This design thus is complicated and leads to significant additional weight. Besides, it is not suitable for refitting existing boat propulsion systems.

DE 296 04 437 describes a similar hybrid propulsion system, comprising a diesel engine, an electric motor and a generator, whose aim is increased fuel economy. Again, this system is not a generator/motor directly mechanically connected to the transmission, nor is it suitable for driving a watercraft whose internal combustion engine has been deactivated. Moreover it cannot be used for subsequently refitting existing boat propulsion systems.

WO 2007/075148 describes a generator/motor, which is integrated in the flywheel housing of an internal combustion engine and serves to generate DC or AC current and acts as an alternative drive unit. This device is not suitable, however, for refitting existing boat propulsion systems. Moreover it will not be possible to operate the watercraft completely decoupled from the generator/motor, resulting in reduced efficiency of the internal combustion engine.

It is an object of the present invention to provide a module of a simple type, which will permit optional propulsion by internal combustion engine or by electric motor or by a combination of both systems, without substantial increase in the total weight of the whole propulsion unit. In a preferred embodiment the internal combustion engine should be able to drive the generator/motor in order to charge the batteries without propelling the craft, if so desired.

This object is achieved by a hybrid module for installation between an internal combustion engine and the transmission of a watercraft. The flywheel is located in a conventional way in the housing of the internal combustion engine, and the hybrid module (7) is external to the housing of the internal combustion engine (6), and comprises a housing (8), a generator/motor (11) within the housing, and suitable shifting elements (10) for optionally coupling the transmission (4) to the internal combustion engine (6) and/or the generator/motor (11). Other advantageous variations or improvements of the hybrid module will be apparent from this disclosure.

The invention will now be described in more detail with reference to the enclosed drawings. There is shown in

FIG. 1 a section through the stern of a watercraft with an internal combustion engine and a propulsion unit comprising transmission, propellers, and a hybrid module positioned between transmission and internal combustion engine;

FIG. 2 a section as in FIG. 1 with a first alternative shifting arrangement in the hybrid module;

FIG. 3 a section as in FIG. 1 with a second alternative shifting arrangement in the hybrid module;

FIG. 4 a section as in FIG. 1 with a third alternative shifting arrangement in the hybrid module;

FIG. 5 a section as in FIG. 1 with a fourth alternative shifting arrangement in the hybrid module;

FIG. 6 a section as in FIG. 1 with a fifth alternative shifting arrangement in the hybrid module;

FIG. 7 a section as in FIG. 1 with a sixth alternative shifting arrangement in the hybrid module;

FIG. 8 a section as in FIG. 1 with a schematical presentation of the generator/motor in radial design surrounding the centric gearshift elements and the main axis in the hybrid module;

FIG. 9 a section as in FIG. 8 with a schematical presentation of the generator/motor in compact design in a position parallel to the main axis in the hybrid module;

FIG. 10 a section as in FIG. 8 with a schematical presentation of the generator/motor in compact design in angular position, for instance at a right angle to the main axis in the hybrid module as shown;

FIGS. 11 to 13 the hybrid module as an add-on module with different mounting flanges;

FIGS. 14 to 19 various embodiments in which the housing of the hybrid module is configured as an extension of the transmission housing.

FIG. 1 schematically shows part of stern panel 1 and bottom 2 of a watercraft. The propulsion unit 3 comprises the transmission 4, which includes first transmission parts and transom panel 4 a and the transmission 4 b proper, as well as propellers 5. The internal combustion engine 6 is located within the watercraft. Between the internal combustion engine 6 and transmission part 4 a the hybrid module 7 is positioned, which consists of the housing 8 and the generator/motor 11, here of the annular type and disposed concentrically around the main shaft 9 and the shifting elements 10. The shifting elements are configured as a freewheel.

This embodiment permits propulsion by the internal combustion engine 6 as well as purely electric propulsion by the generator/motor 11, which in this case acts solely as an electric motor. If the internal combustion engine 6 is used as driving unit the generator/motor 11 acts as generator, powering the onboard electrical installations and charging the battery pack, which supplies energy for the electric motor when the internal combustion engine 6 is deactivated. In order to start the internal combustion engine a separate starter unit is required, however. Mechanical decoupling of the generator is not possible; it may only be electrically decoupled. By appropriate gearshifting in the transmission 4 the drive may operate in forward, reverse or neutral mode.

In the alternative embodiment of the hybrid module shown in FIG. 2 the shifting elements 10 are positive locking clutches, for instance dog clutches, synchronizing devices, etc. As opposed to the variant of FIG. 1 the internal combustion engine can be started in this case when the clutch is engaged. This embodiment permits propulsion by the internal combustion engine 6 as well as purely electrical propulsion by the generator/motor 11, acting solely as electric motor. If the internal combustion engine 6 is used as drive the generator/motor 11 acts as generator. Mechanical decoupling of the generator is not possible. The drive may again operate in forward, reverse or neutral mode.

In yet another alternative variant of the hybrid module shown in FIG. 3 the shifting elements 10 consist of two positively locking clutches. In contrast to the variant of FIG. 2 it is possible in this variant to mechanically decouple the drive via the internal combustion engine from the generator/motor, resulting in better efficiency as compared to the variant of FIG. 2. This variant permits a purely electrical drive, and propulsion solely by the internal combustion engine, and propulsion by the internal combustion engine while the coupled generator/motor charges the batteries, and starting of the internal combustion engine by the electric motor. The drive may again operate in forward, reverse or neutral mode.

An analogous embodiment with three positively locking clutches as shifting elements is shown in FIG. 4. As compared with the variant of FIG. 3 this embodiment has the additional advantage that starting the internal combustion engine by the electric motor or solely charging the batteries from the generator is possible, even in the case of a Z-drive train or with a transmission having no neutral gear position. A further essential advantage of this variant is the possibility of starting the internal combustion engine by the electric motor or of charging the batteries from the generator, even if the Z-drive train is in the lifted position.

FIG. 5 shows an alternative embodiment of the hybrid module of FIG. 2, with the shifting elements 10 here being realized by a friction clutch, for instance a wet multiple disk clutch or a dry clutch. This embodiment permits the same operational modes as that of FIG. 2.

FIG. 6 shows an alternative embodiment of the hybrid module of FIG. 3, with the shifting elements 10 here being realized by two friction clutches. This embodiment permits the same operational modes as that of FIG. 3.

FIG. 7 shows an alternative embodiment of the hybrid module of FIG. 4, with the shifting elements 10 here being realized by three friction clutches. This embodiment permits the same operational modes as that of FIG. 4.

FIG. 8 again shows schematically the design of a hybrid module 7 with annular generator/motor 11, disposed concentrically with the main shaft 9 and the shifting elements 10. Any of the variants of the shifting elements 10 shown in FIGS. 1 to 7 can be employed.

In FIG. 9 there is schematically shown a variant of the hybrid module 7 as an alternative to that of FIG. 8, with the generator/motor here configured as a compact unit, which is not concentric with the main shaft 9 but parallel to it, and is coupled to the main shaft by a spur gear set 12, a chain or belt drive or the like.

A further alternative embodiment is presented in FIG. 10. Here the compact generator/motor 11 is positioned at an angle relative to the main shaft 9, for instance at a right angle as shown, and is coupled to the main shaft via conic gears, crown gears, a worm gear or the like.

FIGS. 11 to 13 show three examples of the use of the hybrid module 7 as a subsequently added module with suitably configured mounting flanges. In FIG. 11 one recognizes a commercially available inboard transmission for shaft drive systems and surface drives with two SAE-7 standard mounting flanges 14, also known as Borg-Warner flanges.

FIG. 12 shows a VOLVO-Penta IPS-drive with corresponding mounting flanges 15 for IPS-drives. FIG. 13 shows a further exemplary internal combustion engine 6 with saildrive 16 and corresponding mounting flanges 17. It should be obvious that the hybrid module 7 as an add-on sandwich part can also be used with other drives, such as MerCruiser stern drives, VOLVO-Penta stern drives, IP-drives, CummingsMerCruiser ZEUS-pod-drives and other variants of drive systems not shown here.

The housing 8 of the hybrid module 7 may also be designed as an extension of the transmission housing. Examples of this version are shown in FIGS. 14 to 19.

FIG. 14 shows a new transom panel 18 with integrated hybrid module 7 and a suitable MerCruiser mounting flange 19. FIG. 15 shows the VOLVO-Penta Z-drive train with matching VOLVO-Penta mounting flange 20 and a new VOLVO-Penta transom panel 21 with integrated hybrid module 7. In FIG. 16 an IP-drive made by GHM with a SAE-7 BW-standard flange 22 and a modified transom housing 23 is shown.

FIG. 17 shows an inboard transmission for shaft drive systems and surface drives with a SAE-7 BW-standard flange 22 and an inboard transmission 24 with integrated hybrid module. In FIG. 18 the integration of the hybrid module 7 in a typical IPS-drive 25 can be recognized. FIG. 19 shows the internal combustion engine 6 of FIG. 13 with a matching mounting flange 17 and a saildrive 16 with a hybrid module integrated in its housing 26.

The great design simplicity of the hybrid module proposed by the invention is of particular advantage. It permits propulsion of a watercraft either by a conventional internal combustion engine or an electric motor, which is designed as a generator/motor and therefore can also be employed for charging the batteries needed for its operation, in addition to enabling propulsion by a combination of both systems.

It is of particular advantage that in electric motor operation electrically reversing the direction of rotation of the generator/motor will provide backward motion, thus eliminating the need for a reverse gear in the transmission. This will simplify the transmission and reduce its weight.

The present invention permits the use of watercraft with internal combustion engines in ecologically sensitive areas and achieves a significant reduction of emission and noise. As a further advantage the total weight of the drive assembly will not be substantially increased. The hybrid module is ideally suited for retrofitting with existing systems, though its housing may also be integrated to advantage into the transmission housing of newly built crafts. 

1. A hybrid module for installation between an internal combustion engine and a transmission of a watercraft, a flywheel being located in a conventional way in a housing of the internal combustion engine, the hybrid module comprising: a housing, a generator/motor within the housing, and suitable shifting elements for selectively coupling the transmission to the internal combustion engine and/or the generator/motor, wherein said hybrid module is external to the housing of the internal combustion engine.
 2. A hybrid module according to claim 1, said hybrid module is configured so as to be installed in the watercraft as a separate part in the form of a sandwich.
 3. A hybrid module according to claim 1, wherein the housing is configured as an extension of a transom panel or of a transom housing of the transmission.
 4. A hybrid module according to claim 1, wherein electrically changing a sense of rotation of the generator/motor in an electric motor mode of propulsion produces backward motion of the watercraft.
 5. A hybrid module according to claim 1, wherein the shifting element is a freewheel.
 6. A hybrid module according to claim 1, wherein the shifting element is a positive locking coupling with one, two or three positive locking clutches.
 7. A hybrid module according to claim 1, wherein the shifting element is a frictional coupling having one, two or three friction clutches.
 8. A hybrid module according to claim 1, wherein the generator/motor is annular and disposed concentric with a main shaft and the shifting element.
 9. A hybrid module according to claim 1, wherein the generator/motor is compact and disposed parallel to a main shaft, and drives the shaft using a spur gear set, a chain drive, or a belt drive.
 10. A hybrid module according to claim 1, wherein the generator/motor is compact and disposed at an angle to the main shaft, and drives the shaft using conical gears, crown gears, or a worm gear.
 11. An application of a hybrid module according to claim 1, wherein the hybrid module is used as a sandwich part with suitably configured housing mounting flanges for diverse internal combustion engines and diverse drive systems.
 12. A hybrid according to claim 6, wherein the positive locking clutch or clutches of the positive locking coupling are dog clutches or synchronizing means.
 13. A hybrid according to claim 7, wherein the friction clutch or clutches of the frictional coupling are wet multiple disk clutches or dry clutches. 